Japanese Laid-Open Patent Publication No. 2001-349110 and Japanese Laid-Open Patent Publication No. 2001-349117 exist as disclosing known electronic key systems for a vehicle. The electronic key systems for a vehicle disclosed in these documents have activation means (switches) arranged in a door handle and trunk lid of the vehicle. If a user operates (activates) these activation means, communication with the electronic key commences, and a comparison is carried out between an ID transmitted from the electronic key and an ID registered in the controller. When the comparison shows that the respective ID's are matched, the door lock is released.
An electronic key system that has a transmission antenna provided for each door of a four-wheeled vehicle, which can release only the door that a portable device is closest to independently of the other doors of the vehicle, has also been proposed as related art (see, for example, Japanese Laid-Open Patent Publication No. 10-317754).
When applying this type of electronic key system to a motorcycle, it is necessary to provide some type of activation means equivalent to the activation means (switches) arranged in the door handle of the four-wheeled vehicle. In addition, when activation operations and the deposit and removal of a helmet from the motorcycle storage container by the user are taken into consideration, it is preferable to provide the activation means at positions that are within the natural reach of the user during these operations, such as on the handlebar or the seat.
The present invention has been conceived in view of this type of problem, and an object of the invention is to provide an electronic key system for a vehicle that can smoothly activate a controller during a series of operations by the user when boarding the vehicle, and which can improve operability of activation using the electronic key.
Another object of the present invention is to provide an electronic key system for a vehicle that can obtain the advantages of being small in size, lightweight and low in cost, without the need to provide a new activation means.